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My rotors are pretty scored - not sure if i need to replace them.
Has anyone done whats this guy does?
Just buy new ones, they're dirt cheap
Well does it matter if the discs are scored? i don't know how it affects performance.
Anyway the guy in the vid just abrades the surface down until the scores are polished out. Removing material. Not sure of there i a minimum thickness requirement for disks. Maybe do it once and then buy new if you really need to.
Roughen them to take a glaze off, maybe. Take a skim off to remove scores, no. Just buy new ones or live with the scores if it isn't eating pads.
If they're still working then what's the issue??
And as per Steveb77, just buy new ones.
The problem with having scored discs (WTF are we calling them rotors like a non English speaker?) is that until the pad material has worn to match the disc scoring you only have (e.g.) 50% of the friction material touching the disc. There is a possibility that the touching brake fiction material might overheat and be ruined (not sure on this, certainly true of car brake pads though).
Sanding brake rotors is just to remove glazing as far as I know. There is no way that you could sand a rotor by hand to remove scoring and maintain a uniform rotor thickness. Varied thickness would cause pulsating in the lever or possibly even the brakes to grab or lock up.
I've never seen a rotor polished to almost a mirror finish like he says in the video. IME, the rotors become scored over time as the rotor wears more where the pad material is harder.
Brakes do have a minimum rotor thickness at which it should be replaced. It varies by brand, as the original thickness of the rotor varies from one brand to another.
Unless your rotors are at the minimum thickness or the scoring is unusually bad, I'd keep using them.